Thermoelectric properties of the tetradymite-type Bi2Te2S-Sb2Te2S solid solution

The thermoelectric properties of the tetradymite-type Bi2-xSbTe2S solid solution (0 <= x <= 2) are reported for the temperature range 5-300 K. The properties of non-stoichiometric, Cl and Sn doped nand p-type variants are reported as well. The Seebeck coefficients for these materials range from -170 to +270 mu VK-1 while the resistivities range from those of semimetals, 2 m Omega cm, to semiconductors, >1000 m Omega cm. Thermal conductivities were low for most compositions, typically 1.5 W m(-1) K-1. Nominally undoped Bi2Te2S shows the highest thermoelectric efficiency amongst the tested materials with a ZT = 0.26 at 300 K that decreased to 0.04 at 100 K. The crystal structure of Sb2Te2S, a novel tetradymite-type material, is also reported. (C) 2009 Elsevier Ltd. All rights reserved.